Gelling reagents for soluble silicates



Utittfid States Patent ICC watts Patented Feb. 3, 1379 493.406 Thevariation of these ratios evidently an influence CEILING REAGENTS FORSOLUBLE on the characteristics of the gels it .15 desired to obtain.

SILICATES The characteristics recognized as being the most impor- Pi F li d B B l, L F tant ones are: gelling time resistance to compression,senassignors to Progil de Miromesnil, Paris, France, a corsitiveness towater and viscosity of the mixture of silicate i poration of France 0and reagent as well as the variation of viscosity with P p N -F i time.It is generally desirable that the gelling time be Claims priority,applicgtion France, Dec. 28, 1965, neither lower than to minutcs norgreater than 1 Int. Cl. Eozd 2 3/00 C04! 7/00 hour, with a time ofapproximately 3:0 to 50 minutes be- CL 1o6 74 7 Claims m mg consideredas a good average. With respect to the resistance to compression,figures of between 10 and 30 kg./cm. are considered to be goodcharacteristics. Finally the initial viscosity of the mixture ofsilicate/ ABSTRACT OF THE DISCLOSURE succinic acid diesters are used asgelling agents for gelling agent must he P y 5 cemi" alkZili metalsilicates in soil stabilization. 15 P0slses that 18 near the vlscosltyof Water- Moreover it must increase with time in a manner that is slowenough to allow, during consolidation of soils, injection operations andcleaning of the apparatus before irreversible gelling.

To obtain these characteristics, when the diester used The presentinvention relates to a new gelling reagent for alkali metal silicates,and more particularly to new compositions containing silica gels whichare transformahls a sohereht hs f as wen as m the use is dimethylsuccinate the ratios of a of between 0.02 and of these gels for soilconsolidation and stabilization. 0.15 and f b of between and 2 are usedIt has been It Is khowh by a'ddmg some orgamc reagents to establishedthat the three pre-cited gel characteristics had alkali metal silicates,it is possible to obtain silica gels their optimum values when variedbetween 0 6 and 1 capable bemg h fi 3 hard mass having (little dilutedsilicate) while a was maintained between cemehthkh charactenshcs- Amongthe numerous i 0.04 and 0.12. Under such conditions, thegelling times:agents which have been suggested heretofore are fatty may vary between5 d 125 minutes, compression acids P l esters q p s fhohoacids such 52%.sistances are greater than 10 kg/cm. and viscosities, ac f amldss ofahphahc acids such as forms ranging about 2 to 6 centipoises immediatelyafter inalkah metal hlcarhOhates, esters of Ell/01s such as chasetroducing the reagent(s) in the silicate, increase slowly at 1 filmi Sof f of these PTOdUCIsfirst, and then assume high values immediatelybefore gel t as now een found thaLsugmiczmid I e ste r s are f ti y goodgelling agents for alkali metal mates the The new compositions accordingto the present inemciehcy which is s y greater than that of the ventionmay be prepared according to conventional known hy i as for elfafhpleeth methods of gelling alkali metal silicates. According to an acetateand then mews, chhtalhlhg cast especially advatnageous method ofoperation, the aqueous 3 free y y group, s for examplesolution of thegelling reagent is introduced during a The diesters usable according tothe present invention period f 1 to 2 minutes into the aqueous Solutionof are dialkyl succihaies i which each alkyl radical may alkali metalsilicate maintained at room temperature, contain 1 to 5 carbon atoms,such as, for example: 40 about 20 methyl, sthyl, P PYL h obutyl, Thecompositions obtained in that way are ready to However it is especiallyadvantageous to use dhhethyl be injected into the soils intended to beconsolidated and/ succinate which has the advantage of good watersolubilor stabilized They are easy to handle and may be i j yintoespecially dense soils, because of their weak initial The diestersaccording to the invention may be used viscosity, which is close to thatof water. They give rise by themselves or in mixture with other gellingreagents of to the formation of extremely resistant gelsi'the. compresaknown type such, for example, as egyl z t ate, ethylsion resistance ofwhich is often greater than 15 kg./cm. glycol acetate, diacetine,triacetine, etc. and which are transformed into a hard and coherentmass,

The ilk ali metal silicates capable of being gelled acr similar tocement. cording to the invention may be sodium, potassium or The amountof such mixtures to be used according to lithium silicates orpolysilicates, in which the molecular the invention, with respect tosoils to be treated, are of ratio of SiO /M O is between 2.0 and 5.0and, prefercourse variable according to the type of soil (clayey, ably3.4 to S. (M=alkali metal.) They are normally used sandy, etc.). Howevergenerally between 10 to 60% of in the form of aqueous solutionstitrating 25 to 40% of the said composition are used with respect to thesoil dry extract, such as, for example sodium silicate solutions weight,that is about 1 to 10% calculated by the weight titrating 31 to 34 Baum(at 20 C.). of the dry extract of the constituents aceording to the Therelative ratios of succinic diester and alkali metal invention, silicatemay vary between large limits. However, the The following examples areillustrative only and should preferred proportions of dialkyl succ natee om 5 o not be construed as limiting the scope of the invention. 50parts-by weight (dry extract) for 100 parts of alkali metal silicate(dry extract). Moreover, when the dialkyl EXAMPLE 1 succinate is used incombination with another gelling agent of a known type, the respectiveratios of the two sales of gels have been p pared by mixing, as ex:

gelling reagents in the mixture may be very large, for plane?herelnllboveiaqueolis Solutlqns of Sodlum i example 100 to parts byweight of Succinate for 0 05 at 31 Baume, having yariable ratios of aand b, with to 40 parts of the other reagent aqueous solutionscontaining 10% of dimethyl succinate. A convenient method to expressconstituent relative 3 g used S'hcate had a molar ratio S'OZ/NMO Equalto gggg g s fi gzg 312223;? ns according to the mvenuon Then thefollowing characteristics of the obtained mixtures have been measured:Teageht Weight Water Volume (a) Gelling time Tp, the time necessary inorder that silicate volume silica e vo ume the surface of a containerfilled with gelling mixture and ti t-93,406

inclined to the horizontal position, does not show any more deformation.

(b) Resistance to compression R, measured by gel resistance to thesinking of a needle having a section of 1.18 cm. this needle beingconnected to a dynamometric ring of 100 kg, on gels having beensubmitted to a 48 hours-aging and kept under mm. of water.

(0) Viscosity V, measured at a temperature of 20" C. by means of theEpprecht viscosimeter of Rheomat 15 type. under.

The obtained results are given in Table l hereinafter. TABLE TABLE lRcsistanccs (average), kg./t:m.'-', Ratio b Ratio :1 Tp Minutes R(kg/cm?) Ratio values 0.6 H 0.04 78 1L3 a b 24h. 48h. 72h- 0.05 45 17.83% g rg-g 83% 3' %:2 i %:2 6 0-035 132 0:06 115 316 31s 318 0.05 67 10.90.06 45 14.5 if 1213 What is claimed as: l g A composition of matterconsisting essentially of 1 5 (1) an aqueous solution of up to 40%alkali metal sili- -g' 'i' i? %%-g cate and (2) a gelling agent for saidsilicate comprising a 1 1 r dialkyl succiriate in which each alkylradical has 1-5 5 carbon atoms, the respective weight ratios, as dryextracts,

being 5-50 parts by weight of saidgelling agent for 100 parts by weightof said alkali metal silicate. Ram) Rum) Minulls R (kl! 2. A compositionof matter according to claim 1, 1.2 0 045 210 1 2 wherein the dialkylsuccinate is dimethyl succinate.

, gg 2: g-g 3. A composition in accordance with claime 1, wherein in 211 said gelling agent comprises up to 40% by weight of an other gellingagent. 1.5 178 4. A composition of matter in accordance with claim 1, ggg2 2 3 wherein said alkali metal silicate has a molar ratio 34 5 SiO /MO between 2.0 and 5.0, wherein M is an alkali 53g metal, said alkalimetal silicate being selected from the 15 4 1 group consisting of sodiumlithium and W 0.18 10 7.0

For the mixtures described in the table hereinabove, the initialviscosity of the gelled silicate solution varies between 1.5 and 5centipoises. The viscosity of a composition having a molecular ratio SiO/Na O=3.92 and for which 0:006 and b=0.8 was 6 centipoises after 15minutes and 10 centipoises after 34 minutes, gelling time being aboutminutes.

As may be noted, the best results are obtained when a sodium silicate ofhigh molecular ratio SiO /Na O (equal to or upper than 3.90 is used) anda ratio b (water volume/silicate volume) is chosen which is lower thanor equal to 1. In this case the compression resistance of the gels reachas high as 28 kg./cm. Moreover the gels obtained are extremely resistantto water action; some of them have been. kept in water for more than onemonth, with a ponderal rate of degradation lower than 1%.

EXAMPLE 2 In order to show the consolidated power of the com-- positionof a silicate and succinic diester on non-coherent materials, tests havebeen made on dry Fontainebleau sand.

For this, test-tubes having a diameter of 37.5 mm. and a height of 75mm. have been filled with this sand. These test-tubes are submitted to alight vibration movement, without any compression, then the sand hasbeen impregnated by capillarity with the gelling mixtures obrainedaccording to Example 1. The quantity of gelling mixtures vary between 1and 10% of the weight of sand (expressed in dry extract).

Then the test-tubes prepared in that way have been tightly shut in orderto keep the mixtures sheltered from air. Compression resistance measureshave been made respectively during 24, 48 and 72 hours after treatment.

The results obtained are given in the Table II here-- cates andpolysilicates.

A composition of matter in accordance with claim 1., wherein saidaqueous solution of alkali metal silicate comprises 25-40% by weight ofdry alkali metal silicate.

6. A composition of matter in accordance with claim 5, furthercomprising additional water, said composition of matter being of lowviscosity.

7. In a process for the consolidation and stabilization of soils bymixing with said soil a composition compris ing an aqueous alkali metalsilicate and a gelling agent for said silicate, so that a gel is formedwithin said soil, the improvement consisting essentially of:

using the composition of claim 1, in a quantity of 110% as a dry extractwith respect to the soil weight, together with additional water toprovide a low viscosity composition, and

effecting said mixing with the soil by injecting said low viscositycomposition into said soil.

References Cited UNITED STATES PATENTS 50 2,766,130 10/1956 Dietz 106-742,809,l18 10/1957 Keil 106-84 JAMES E. POER, Primary Examiner U.S. c1X.R.

